The United States will track down Usama bin Laden wherever he goes, Secretary of Defense Donald H. Rumsfeld told reporters Thursday. 

"I think we will find him, either [in Afghanistan] or in another country," Rumsfeld said. 

Gen. Tommy Franks, commander of the Afghan campaign, said that while the Taliban have not been destroyed, the United States definitely has the momentum in the war against terrorism. 

Asked how the weeks of bomb strikes have gone, Franks said, "The Taliban is not destroyed as an effective fighting force." But the U.S. military "will do our best to eliminate that force." 

"We'll remain steady on the course," said Franks. "We have the initiative; we intend to maintain the initiative." 

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Military activity Thursday included American airstrikes against Taliban positions near the city of Kunduz in northern Afghanistan, where militia members and their Al Qaeda allies, surrounded by Northern Alliance forces, were making a last stand in a pocket of ethnically Pashtun territory pressed up against the border with Tajikistan. 

Hundreds of miles to the south, the Taliban appeared to be in control of their birthplace and spiritual home, the city of Kandahar. But an anti-Taliban source in Pakistan told the Associated Press that militia fighters were surrounded by anti-Taliban Pashtun tribesmen, and an American official reported sporadic street fighting. 

The Pakistani source, who spoke on condition of anonymity, said the Pashtuns were trying to convince Taliban leaders to hand bin Laden over. The claim could not be independently confirmed. 

Earlier Thursday, Pentagon spokeswoman Victoria Clarke said senior members of the Taliban and Al Qaeda were killed in American airstrikes on two buildings outside Kabul on Tuesday. 

She had no numbers or identities of the people who died. 

"There was some senior leadership. ... No evidence that it was Usama bin Laden," Clarke said. "One of our primary objectives over the last few days has been to go after command and control — Taliban and Al Qaeda leadership." 

Clarke declined to say whether officials believe bin Laden is still in Afghanistan. "We don't have him," she said. 

Asked if he is still alive, she said, "We've heard nothing to indicate otherwise." 

Clarke said there would be no letup in bombing during the Muslim holy time of Ramadan, which begins this weekend. 

"The terrorists don't take a break; we don't take a break," she said. 

The Taliban were fighting in only three areas — in two pockets at Kunduz and near Baghlan in the north, and in the streets of Kandahar in the south, said a U.S. official in Washington, speaking on the condition of anonymity. 

Anti-Taliban Pashtun forces have seized power in the towns and provinces between Kabul and Kandahar, the official said, adding that the Northern Alliance has consolidated its gains as far south as Farah province in western Afghanistan, and that anti-Taliban Pashtuns were in control of Nimruz province. 

In northern Afghanistan, anti-Taliban forces said they were preparing to launch an offensive against the front line outside Kunduz, the region's only city of significant size remaining under Taliban control. The front line was just west of Bangi, a village about 30 miles east of Kunduz, which lies between the Northern Alliance-held cities of Mazar-e-Sharif and Taloqan. 

U.S. warplanes launched dozens of strikes against Taliban tank and troop positions in the area, refugees and witnesses said. 

Refugees coming out of Kunduz on a paved road said the bombs were hitting their targets — on both sides of the road. 

"On one hill there were a lot of Taliban, and after the U.S. bombs hit, there was nothing living there," said 20-year-old Jaglan Mohammed Sakhay. 

There are 20,000 to 30,000 Taliban who are holding Kunduz, among them 6,000 foreign fighters — including Chechens, Burmese, Pakistani and Chinese — tied to Al Qaeda, said Gen. Daoud, the Northern Alliance commander in charge of the siege of Kunduz. 

Northern Alliance commanders said they were trying by radio to get the Taliban to surrender, but Sayaf Baick, a Northern Alliance commander, said the foreign fighters had killed several local Taliban officials in Kunduz who wanted to give up the city. 

"For the foreign terrorists ... there will be no negotiations, we will not deal with them, they are killers," Daoud said, citing their alleged role in the assassination of Northern Alliance leader Ahmed Shah Massood. 

"The foreigners are living between life and death. They are desperate and they are trying everything," Daoud told a news conference in Taloqan. 

Daoud said the mayor of Kunduz has asked for two days — Thursday and Friday — to try to negotiate the Taliban surrender of the city to avoid civilian casualties. 

"He was negotiating himself with the foreign fighters, who are not ready to surrender." 

Just who was in control of particular areas was difficult to pin down. The Taliban were reported to have left the eastern city of Jalalabad, but one Shiite Muslim Northern Alliance leader, Saeed Hussein Anwari, told The Associated Press in Kabul on Thursday that the city's status was unclear. 

Philip Smith, the Washington liaison for Gen. Dostum, a Northern Alliance commander, said Wednesday that a force of roughly 5,000 fighters were moving toward Kandahar in light trucks and on horseback from the western city of Herat. 

The rebels were encountering stiff resistance from Taliban Pashtuns in the mountains of southwestern Afghanistan. U.S. Green Berets were traveling with the force, he said. U.S. officials could not verify this report. 

Supreme Leader Calls for 'Extinction of America' 

Taliban supreme leader Mullah Mohammed Omar, defiant despite the series of stunning setbacks in the last week, told the BBC Thursday that the Taliban pullback from urban centers was part of a larger strategy that aims to destroy America. 

"If God's help is with us, this will happen within a short period of time — keep in mind this prediction," he said. 

"The real matter is the extinction of America, and God willing, it will fall to the ground." 

Omar also ruled out taking part in a multiethnic government that the United Nations has proposed for Afghanistan, saying he'd rather die than join an "evil government." 

Fox News' Bret Baier and The Associated Press contributed to this report